[Forwardport] Remove unused namespace from ui export

[dmytro-ch]

Original Pull Request

#15240

Description

The Export model have some unused namespaces: Magento\Framework\Filesystem\Directory\WriteInterface.
Just removing it and update description

Manual testing scenarios

1. For example, go to orders list;
2. Export list of order by XML or CSV;
3. All should export as expected.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[rogyar]

Seems like there's some mistake. In the constructor we init $directory property as a result of $filesystem->getDirectoryWrite() method, which creates an instance of Magento\Framework\Filesystem\Directory\Write using the corresponding factory. So, basically, it returns WriteInterface but not DirectoryList. The same situation is for the ConvertToXml class.
Please, correct me if I'm wrong.

[dmytro-ch]

@rogyar thank you for notice. You are right. We should close this pull request.